399879 divided by 12 
We want to divide 399879 by 12.

Advancing to step 1:
12 can be fit into 3 0 times, resulting in a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 12

Advancing to step 2:
The number 12 fits into 39 3 times, leaving a remainder of 3.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtract 36 from 39 to get 3.
Include the next digit (9) from the dividend after 3, then repeat: 39 / 12

Step 3:
If we divide 39 by 12, we get 3 and a remainder of 3.
Record the quotient 3 as the next digit in the result. 
Result so far: 33.0
Subtracting 36 from 39 leaves us with 3.
Append the next digit (8) from the dividend to 3 and continue with: 38 / 12

On to step 4:
12 goes into 38 3 times with a remainder of 2.
Write down 3 as next digit of the result. 
Result so far: 333.0
Deduct 36 from 38 and we're left with 2.
Include the next digit (7) from the dividend after 2, then repeat: 27 / 12

Going ahead to step 5:
12 can be fit into 27 2 times, resulting in a remainder of 3.
Write down 2 as next digit of the result. 
Result so far: 3332.0
Deduct 24 from 27 and we're left with 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 12

Let's proceed to step 6:
39 divided by 12 is 3 with a remainder of 3.
Write down 3 as next digit of the result. 
Result so far: 33323.0
If we take 36 away from 39, we end up with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

On to step 7:
30 divided by 12 is 2 with a remainder of 6.
The next digit of our result is 2. 
Result so far: 33323.2
The remainder is 6 after subtracting 24 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
If we divide 60 by 12, we get 5 and a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 33323.25
If we subtract 60 from 60, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
When dividing 0 by 12, we get 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 33323.25
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 10:
12 goes into 0 0 times with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 33323.25
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 33323.25, with a leftover of 0.0.